Colored granule, etc.



COLORED GRANULE, ETC

Filed April 18, 1929 RNEYS Patented-Nov. 3, 1931 UNITED Isiixras PATENT `ori-"lcs mA: ELHEB SPROAT. 0F COVINGTON, `OHIO, ASSIGNOR T0 E T. VANDEBILT'COMPANY, INCORPORATED, OF NEW YORK, N. Y., v

.A CORPORATION 0F NEW YORK (ZOLORED GRANULE, ETC. Application med April 18, 1928. Serial No. 356,084.

This invention relates to new colored granules suitable for sufacin rooting` or for architectural surfaces. ore particularly the invention is concerned with colored granules produced by colorin crushed rock or similar material without 'sostantially changin its size or formation and'without the use 053x sive ap aratus or high temperatures.

It as been t e ractice for a long time in the manufacture o? roofing materials to press a layer of crushed rock into the upper surface of the bituminous or mineral cement which forms the body of the roofing material.- This layer of rock serves at the same time'to protect the body of the roofing material from the weather and, particularly in the case of crushed slate, to give to the surface a color which is more easing than that of the body of. the material. f

In the past the colors which it has been 'possible in this manner to provide on roofing materials has been limited by the ranve of naturall occurring minerals which cou d be obtaine in uantity and at a price such as to permit of ilieir use in this manner.

I have now discovered a process by which .such granules of rock or similar materialv can be given almost any desired color without impairin its desirable qualities and wlth only a s ight increase in the cost of the material.

By my new process I am enabled to produce a permanent color on the material without the use of high temperatures and with only the simplest of apparatus.

In the accompanying drawing I have illustrated an apparatus suitable for use in preparing my new colored granules.

To prepare my new anules, the rock or other similar material 1s crushed to 'the desired size and is then treated with a solution of cellulose or cellulose derivatives, such as the ordinary brushing or s raying lacn quer, which contains suitable yes or gig! ments to provide the desired color. he

solutions which I prefer to use are those which have been developed for .finishing automobiles, as these have been designed to withstand servere conditions of weathering while retaining their color` and finish." Suc lacquers may be obtained in a wide variety of colors. The lacquer may be ap lied to the granules 1n any sultable manner. owever, I have discovered that elaborate pre aration of the material is not essential an cation of the lacquer to the granules may be accomplished at almost negligible expense by the use of an apparatus such as I have illustrated diagrammatically in the drawing.

size previously freed from pulverized rock 'by screeninlg onpassing through an air current or by ot er suitable means, are supplied to the hopper 1, from which they fall into the rotary mixer 2. The lacquer is contained in the reservoir 3 from which it ma be fed by gravity or suitable pressure through the pipe 4, into the mixer 2.

T e mixer 2 is of a-size and rotates at a speed such that the granules are thoroughly mixed together and coated with a thin layer of the lacquer during their assage through the mixer. The amount ci) lacquer which is admitted into the mixin chamber is proportioned to the charge o granules, so that each granule will bercovered with a continuous thin layer of the lacquer without leaving any excess to be drained from the coated granules. r l y The granules, after they are thoroughly coated with the lacquer, are caught in the trough 5 and transferred thereby to a second rotary mixer 6. In the second mixer a draft of a suitable gas, preferably an inert gas 'such as carbon dioxide, or nitrogen, is maintained bythe blower 7. This mixer may A lbe heated by suitable means in order to hasten the drying operation or the stream .of gas' which is `supplied thereto may be heated. Such heating, however, is not essential. The rotation of the mixer 6, causes the granules to fall over each other and through the s ace within the mixer, thereby preventing t em from adhering to each other in a solid massthat the appli- The granules of crushed rock of suitable an their coating thoroughly dried, are collected by the trough 8 and transferred to any suitable receptacle 9. The vapors of the solvent are preferably drawn off through the conduit 10 to a solvent recovery apparatus 1l, where the vapors are condensed and recovered in a form suitable for reuse in the manufacture of more cellulose lacquer. The gases whichpass off from the solvent recovery apparatus are preferably returned to the blower 7 by the conduit 12, thus avoiding the discharge of objectionable odors into the atmosphere and retaining any unrecovered solvent, or inert gas if such is being used, within the cycle. Y

It is to be understood that the yabove described apparatus is merely exemplary and that the preparation of my colored granules is not limited to the use of the particular apparatus described. I have indicated the mixers as being of the common type of continuous mixers such as are used in the mixing of .Portland cement to form concrete. However,

many different types of mixing apparatus will be recognized as more ,or less suitable for use in preparing my colored granules. Instead of using a continuous mixer the operation may be made intermittent, the mixer being fully charged and operated until the mixing is complete and then the entire charge transferred to the drying mixer; or the coating and drying may be formed in,- the same mixer, by first introducing the charge of granules and lacquer, then operating the mixer until the coating is complete and thereafter introducing a stream of a drying gas until the solvent is substantially evaporated and carried off, after which the charge may be removed from the mixer vand transferred to any suitablev receptacle.

Instead of drying the granules in a mixing apparatus as described, they may be projected into a drying medium in a manner such that they remain separate until the coating is substantially dried. A suitable apparatus for this purpose is a tower of sufcient height so that the granules, when dropped from the top, will be substantially dried before they reachl the bottom. A

strong upward current of a drying gas in' able nozzle or by distributing from a rotary disk or any other convenient manner which will distribute the granules more or less evenly throughout the tower.

While I have found that-a is desirable to use colored lacquers -such as are prepared fori use on automobiles, itis possible in some instances'to use a clear' lacquer and introduce the coloriin dry form with the granules.

Following the method which I have deresults and for this purpose, where a particularly fine result is required, I have found that the mineral pyrophyllite 1s preeminently suitable. Since many lacquers give films that are more or less translucent,the use of different mineral granules having different natural colors or shades makes it possible to obtain a variety of shades with the same lacquer; and thus by mixing a number of different kinds of granules variegated eects might be obtained.

While I have described the granules above as being intended for use on roofing materials, it is to be understood that the colored granules are equally suitable for use in surfacing stucco or plaster on exterior or interior walls or in other places and with other types of material where a rough surface of a.

colored material is required.

It has been proposed prior to my invention to coat roof surfacing grit with a material made from a drying oil and a pigment.

Such a meth 3d, however, is quite unsatisfactory, since the time required'for drying the oil is so great that any possible' method of keeping the granules separated during the drying and prior to application ,to the surface where they are to be used is prohibitively expensive.

t at lacquer such as cellulose lacquer not only dries quickly so as to permit its economical application to the granules, but, if yit is suitably agitated, as described above, durlng the drying process, that each l l anule retains its continuous coating of dried lacquer substantially unimpaired and withou Aadhering to other granules.

I claim: 1. Granules of crushed rock or similar materials enveloped in a thin film of a cellulose derivative,.said film containin a suitable weatherproof coloring materia I have discovered, however,

2. Granules suitable for facing architectural surfaces, and the like, comprising 'granules of a crushed mineral enveloped in a translucent lm of cellulose nitrate, said film containing coloring material.

'a suitable weatherproof v In testimony whereof I aiixmy si ature.

IRA E. SPR AT. 

